Ribbon feeding and reversing mechanism for typewriters and the like



NOV. 9, 1954 N E J STAHL ETAL 2,693,871

RIBBON FEE'DIN'G AND REVERSING MECHANISM FOR TYPEWRITERS AND THE LIKE Filed Aug. 23, 1951 I INVENTORS (Dace/z. W

A RNS United States Patent RIBBON FEEDING AND REVERSING MECHANISM FOR TYPEWRITERS AND THE LIKE Nils Evert Johan Stfihl, Stockholm, and Oscar Uno Larsson, Malarhojden, Sweden, assignors to Almex Inc., Panama Application August 23, 1951, Serial No. 243,322

1 Claim. (Cl. 197162) The present invention relates to the ribbon mechanism in typewriters, calculating machines, cash apparatus and the like and concerns a driving device for the ribbon spools, which offers greatadvantages over the driving devices hitherto known for this purpose, above all with regard to the place required and reliability of service as well as to simpleness of design.

A practical embodiment of the invention is illustrated in the accompanying drawings, in which Fig. l is a diagrammatic perspective view of the complete ribbon mechanism, while Figs. 2-5 show the driving device in perspective and partly broken in different stages of its operation for re versing the direction of motion of the ribbon.

Referring now to the drawings, the numerals 1 and 2 in Fig. l designate two ribbon spools, between which a ribbon 3 is running while being repeatedly wound off one spool and wound up on the other one. The two ends of the ribbon 3 are secured to the respective spools 1, 2 so that the motion of the spools is checked when the ribbon is wound entirely off one of the spools. The ribbon spool 1 is unturnably connected to a gear wheel 4, which receives its motion through a gear wheel 5 meshing with the same, said latter gear wheel 5 forming part of a driving device which constitutes the object of this invention. The other spool 2 is unturnably connected to a gear wheel 6 which via an intermediate gear 7 is in connection with a second gear wheel 8 of the driving device. The driving device furthermore comprises a third gear wheel 9 which is rotated permanently in one and the same direction by a distribution gear 10. The distribution gear 10 receives its motion from some arbitrary member of the apparatus comprising the ribbon mechanism. Of course the distribution gear may be replaced by some other driving member, for instance a reciprocating conveyor of ratchet type. The object of the driving device is to drive the ribbon spools 1 and 2 alternatively, releasing the other spool, while the driving device itself is in turn driven permanently in the same direction, and to cause a shifting of the driving force to the emptied spool responsively to the braking effect exerted when the ribbon 3 has been entirely wound off one of the spools 1, 2 and the ribbon thus prevents the continued rotation of the spools in the recent direction of winding, all to the purpose that during the continued action of the driving device the ribbon shall be wound from the full spool to the empty one while permanently being drawn towards the spool on which it is momentarily being wound up.

The constructional details of the driving device will be apparent from Figs. 25. The driving device is carried by a shaft 11, which to advantage may be stationary and thus only serves to carry the three gear wheels 5, 8 and 9 of the driving device. The two gear wheels 5 and 8 of the driving device, which are connected with the ribbon spools, are uniform and journalled so as to be freely rotatable in nave flanges 12 on either side, as viewed in the axial direction, of the driven gear wheel 9, which in Figs. 2-5 is given teeth of another type than those of the gear wheels 5 and 8 in order to secure greater clearness. The gear wheels 5 and 8 are comparatlvely thin and are held in their position relative the nave flanges 12 of the driven wheel 9 by means of a riveted central sleeve 13, which is provided with suitable flanges. The gear wheels 5 and 8 are pressed tightly against the side faces of the driven wheel 9 and on the 2,693,871 Patented Nov. 9, 1954 ice side facing the wheel 9 they are provided with a number of conical recesses 14 which, due to the small thickness of the gear wheels 5, 8, open towards the outside of said wheels, as well as with projection 15 preferably consisting of depressed portions of the gear wheels and 8 respectively, said projections merging wedge-llke in both directions of their path of motion into. the plane of the respective gear wheel which faces the driven wheel 9, the path of motion meaning the path described by the respective gear wheels when rotating about the shaft 11, which forms the centre of all wheels in the driving device. On its two side surfaces, which are facing the respective gear wheels 5 and 8, the driven wheel 9 is provided with annular grooves 16 serving to receive the projections 15 of the respective gear wheels and allow their free passage at relative rotation between the wheels 5, 8 and 9.

At the same distance from the centre as the conical recesses 14 in the gear wheels 5 and 8 is an axially through passing hole 17 in the driven wheel 9, and into this hole 17 opens a hole 18 extending radially from the centre of the wheel 9 and arranged right in the middle between the two side surfaces of the wheel 9. Said radial hole 18 has the same diameter as the axial hole 17 and accommodates a pin 19, one pointed end of which projects radially into the axial hole 17 as actuated by a small compression 21 resting against the riveted nave sleeve 13. In the axial hole 17 in the wheel 9 there is loosely inserted a ball 22, which by the pin 19 is pressed resiliently against that side of either gear wheel 5 or 8 which faces the Wheel 9. The annular grooves 16 in the wheel 9 are passing the axial hole 17 slightly outside of the hole centre as viewed from the shaft 11, but still so that when passing over the hole 17 the lugs 15 on either gear wheel 5 or 8 can actuate the ball 22. Because the actuation of the ball 22 by the lugs takes place outside of the ball centre, the ball will get sufficient room by depressing the pin 19 even in case a lug 15 on both gear wheels 5 and 8 should happen to actuate the ball simultaneously.

In the stage shown in Fig. 2, the gear wheel 8 is brought to partake in the rotation of the driven wheel 9 thereby that the ball 22 is pressed down into one of the conical recess 14 in the gear wheel 8 by the pin 18, whereas the gear wheel 5 can rotate freely relative to the driven wheel 9. The motion of the driven wheel 9 is thus transmitted one-sidedly to the gear wheel 8 and further via the intermediate gear 7 and the gear wheel 6 to the ribbon spool 2 in Fig. l, on which the ribbon 3 is Wound up. When the entire length of the ribbon has been wound up upon the spool 2, the latter and thus also the gear wheel 8 can no longer rotate in the previous winding-up direction, for which reason the continued rotation of the driven wheel 9 will bring about a relative movement between the wheel 9 and the gear wheel 8, with the result that the ball 22 is drawn up from the conical recess 14, at the same time pressing the pin 19 somewhat into the radial hole 18. This stage is illustrated in Fig. 3. At the continued relative movement between the wheel 9 and the gear wheel 8, one lug 15 of the gear wheel .8 will actuate the ball 22 and push the latter part the point 20 of the pin 19 in the axial hole 17. See Fig. 4. As soon as the ball has passed the point 20 of the pin 19, the pin will press the ball against the other upper gear Wheel 5, where the ball will in time click into a conical recess 14, the driven wheel 9 consequently during its continued rotation bringing along the gear wheel 5 and its motion being transmitted via the gear wheel to the other, empty ribbon spool 1, so that the ribbon 3 is wound up upon the latter. This last stage in the reversing operation is illustrated in Fig. 5. Of course the proportions between the lugs 15 on the two gear wheels 5 and 8, the thickness of the driven wheel 9-corresponding to the distance between the opposite sides of the gear wheels 5 and 8-and the diameter of the ball 22 must be so chosen that the function described above is obtained This means that the diameter of the ball 22 is substantially half the thickness of the driven wheel 9 and that the height of the lugs 15 slightly exceeds a quarter of the thickness of the driven wheel 9.

()f Course the driving device may be provided with more conveying means corresponding to the pin 19 and the ball 22 if this is deemed desirable for instance in order to obtain a quicker reversing of the winding-up direction of the ribbon. However, such a quicker operation is also obtainable by arranging the lugs 15 and the recesses 1d nearer each other in the two gear wheels 5' and- S', still using a single ball 22 as shown the embodiment exemplitied in the drawing.

We claim:

In a ribbon mechanism for typing machines, a driving and reversing unit comprisingv incombination a main Wheel having an eccentric axial bore therethrough, and having a radial bore opening into said axial bore, said radial bor'e having the safne diameter as said axial bore, a free ball in said axial bore, a spring-actuated pointed piston slidably mounted said radialbore and exposing its point in said axial bore, said main wheel having an annular groove in each side passing through said axial bore, an outer wheel rotatably mounted close to each side of said main wheel, a plurality of conical recesses in the inner side of each of said two outer wheels, said conical recesses being located at the same radial distance as said axial bore of said main wheel, a plurality of lugs on the inner side oi each of said two outer wheels, said lugs entering said annular grooves of said main wheel and being disposed between said conical recesses, said lugs being" adapted to push said ball from one side of said pointed piston to the other at relative angular movement between said main Wheel and either of said outer wheels.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 456,808 Ford July 28, 1891 1,027,732 Hopkins- .-..e May 28-, I912 

